<ul class="layui-nav layui-nav-tree" lay-filter="side-main">
    {volist name="left_menu" id="val"}
        <li class="layui-nav-item">
            <a href="javascript:;"><i class="layui-icon">&#{$val.ico};</i>{$val.name}</a>
            <dl class="layui-nav-child">
                {volist name="val['sub']" id="sval"}
                    <dd><a href="javascript:;" href-url="{:url($sval['module_name'].'/'.$sval['action_name'], array('menuid'=>$sval['id']))}{$sval.data}" data-id="{$sval.id}"><i class="layui-icon">&#{$sval.ico};</i>{$sval.name}</a></dd>
                    {/volist}
            </dl>
        </li>
    {/volist}
</ul>